JP2000348736A - Solid electrolytic fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid electrolytic fuel cell capable of possibly improving heat resistance in a solid electrolytic element and characteristics of power generation such as discharge current density, generated current density and the like. SOLUTION: This solid electrolytic fuel cell is provided with a solid electrolytic element 16A in which electrodes 12 and 14a are formed on both surfaces of an oxygen ion conductive type solid electrolytic substrate 10. With the solid electrolytic fuel cell, oxygen is supplied to the electrode 12 of a cathode side in the solid electrolytic element 16A, while methane gas as fuel is supplied to the electrode 14a of an anode side therein. Metallic oxide particles 20 and 20... constituted of a CoNiO2 are blended as an oxidation catalyst of the methane gas in a porous platinum layer substantially forming the electrode 14a of the anode side in the solid electrolytic element 16A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolyte fuel cell, and more particularly, to a solid electrolyte fuel cell comprising a solid electrolyte element having electrodes formed on both surfaces of an oxygen ion conductive solid electrolyte substrate, and a cathode of the solid electrolyte element. The present invention relates to a solid electrolyte fuel cell in which a gas containing oxygen is supplied to an electrode on the anode side and methane gas as fuel is supplied to an electrode on the anode side.

[0002]

2. Description of the Related Art Solid electrolyte fuel cells can be expected to have higher power generation efficiency than power generation efficiency such as thermal power generation. As shown in FIG. 10, such a solid electrolyte fuel cell has a yttria (Y ₂
O ₃ ) -added stabilized zirconia (hereinafter simply referred to as YS)
Z (hereinafter sometimes referred to as Z) (hereinafter referred to as YSZ).
(Which may be referred to as a fired body) as an oxygen ion conduction type solid electrolyte substrate 100.
A solid electrolyte element 106 having electrodes 102 and 104a formed on both surfaces of the solid electrolyte element is provided. This solid electrolyte element 1
06 among the electrodes 102 and 104a, lanthanum strontium manganese oxide [(La _0.85
Sr _0.15 ) _0.90 MnO ₃ ] and used as an anode. Oxygen or an oxygen-containing gas is supplied to the electrode 102 side. The other electrode 104a is
It is formed by a porous platinum layer and used as a cathode. Methane gas as fuel is supplied to the electrode 104a side.

[0003] The solid electrolyte element 106 shown in FIG.
(O 2) supplied to the electrode 102 of _Two) Is the electrode 102
Oxygen ions (O 2) at the boundary between^2-)
The oxygen ion (O^2-) Is a solid electrolytic
Conducted to the electrode 104 by the quality substrate 100. Electrode 1
Oxygen ion (O^2-) Is the electrode 104
Supplied to the reactor (CH_Four) Reacts with gas and water (H_Two
O), carbon dioxide (CO_Two), Hydrogen (H_Two), Carbon monoxide
Element (CO) is generated. During this reaction, oxygen ions
Since the electrodes emit electrons, the electrodes 102 and 104a
, A potential difference occurs. Therefore, the electrodes 102, 104
a by electrically connecting the
And the electrons on the electrode 104a move in the direction of the electrode 102 (the direction
Flow from the solid electrolyte fuel cell
I can take my mind. In addition, the fixation shown in FIG.
The operating temperature of the body electrolyte fuel cell is about 1000 ° C.

Although the solid electrolyte element 106 shown in FIG. 10 has durability against a high operating temperature, it has low power generation characteristics such as a generated current density and a discharge current density, and improvement of these properties has been demanded. . For this reason, the solid electrolyte element 110 shown in FIG. 11 is being used. The solid electrolyte element 110 is substantially formed by a solid electrolyte substrate 112 made of YSZ.
12 is formed on one end side of the electrode 104b as a cathode. The electrode 104b includes YSZ forming the solid electrolyte substrate 112, cermet particles 114 made of nickel (Ni) and nickel oxide (NiO),
.. Are formed as a mixture.
The electrode 102 as an anode formed on the other end side of the solid electrolyte substrate 112 is made of a porous platinum layer, like the electrode 102 of the solid electrolyte element 106 shown in FIG.

[0005]

According to the solid electrolyte fuel cell using the solid electrolyte element 110 (hereinafter sometimes referred to as a Ni-YSZ cermet solid electrolyte element 110) shown in FIG. Power generation characteristics such as current density can be improved as compared with the solid electrolyte fuel cell using the solid electrolyte element 106 shown in FIG. However, FIG.
The solid electrolyte fuel cell using the solid electrolyte element 110 shown in (1) has an operating temperature at which electric power can be stably taken out is about 920 ° C. or higher, and at an operating temperature lower than 920 ° C.,
It is difficult to extract power stably. On the other hand, 92
At an operating temperature of 0 ° C. or higher, a phenomenon occurs in which the activity of the solid electrolyte substrate 110 gradually decreases. Therefore, improvement in heat resistance of the solid electrolyte substrate 110 is required. Further, when methane gas in a dry state from which water is removed is supplied as methane gas to be supplied as fuel to the electrode 104b as an anode, the reactivity between methane gas and oxygen ions is insufficient, and the performance of the solid electrolyte fuel cell is reduced. Not fully demonstrated. For this reason, under the present circumstances, in order to ensure the reactivity between methane gas and oxygen ions, a wet menthan gas containing water is supplied to the electrode 104b side. However, since the reaction between the methane gas and the high-temperature steam is an endothermic reaction, the temperature of the electrode 104b decreases, and the carbon generated as the reaction temperature decreases adheres to the electrode 104b. It promotes a decrease in activity and makes stable power generation difficult. Therefore, an object of the present invention is to provide a solid electrolyte fuel cell capable of improving power generation characteristics such as discharge current density and generated current density and heat resistance of a solid electrolyte element as much as possible.

[0006]

The inventors of the present invention have studied to solve the above-mentioned problems. According to the solid electrolyte fuel cell using the solid electrolyte element 200 shown in FIG.
It has been found that power generation characteristics such as discharge current density and generated current density can be improved and power generation can be performed stably even at an operating temperature of less than 920 ° C., as compared with the solid electrolyte fuel cell shown in FIG. Therefore, some of the present inventors have reported that a solid electrolyte fuel cell using the solid electrolyte element 200 shown in FIG.
in Battery & Battery Materials, Vol.17, April (199
8), p.137-143. In the solid electrolyte element 200 shown in FIG. 12, electrodes 102 and 104c are formed on both surfaces of a solid electrolyte substrate 100 made of a YSZ sintered body, and the electrode 102 used as a cathode is made of lanthanum strontium manganese oxide [(La _{0 . 85} Sr
_0.15 ) _0.90 MnO ₃ ]. Also,
Metal oxide particles 2 made of PdCoO ₂ are provided on the porous platinum layer forming the electrode 104c used as the anode.
. 02, 202... However, the power generation characteristics such as the discharge current density and the generated current density of the solid electrolyte element 200 shown in FIG. 12 were still at an insufficient level.

[0007] For this reason, the present inventors have studied a solid electrolyte fuel cell that can further improve the power generation characteristics such as discharge current density and generated current density and the thermal chemical stability of the solid electrolyte element. An electrolyte fuel cell including a solid electrolyte element in which metal particles made of CoNiO ₂ are blended in a porous platinum layer forming an electrode on the anode side, or PdCo on a surface of the porous platinum layer forming an electrode on the anode side.
According to the electrolyte fuel cell including the solid electrolyte element in which metal oxide particles composed of O ₂ are dispersed and fixed, power generation characteristics such as discharge current density and generated current density and heat resistance of the solid electrolyte element can be significantly improved. Found and arrived at the present invention. That is, the present invention includes a solid electrolyte element in which electrodes are formed on both surfaces of an oxygen ion conductive solid electrolyte substrate, and oxygen or an oxygen-containing gas is supplied to a cathode electrode of the solid electrolyte element. In a solid electrolyte fuel cell in which methane gas as a fuel is supplied to an anode electrode, CoNiO _{2 is} used as an oxidation catalyst for methane gas in a porous platinum layer which substantially forms an anode electrode of the solid electrolyte element. Alternatively, there is provided a solid oxide fuel cell comprising metal oxide particles made of CoO.

Further, the present invention comprises a solid electrolyte element having electrodes formed on both surfaces of an oxygen ion conduction type solid electrolyte substrate, wherein oxygen or an oxygen-containing gas is supplied to a cathode electrode of the solid electrolyte element. In addition, in a solid electrolyte fuel cell in which methane gas as fuel is supplied to the anode electrode, PdCoO as an oxidation catalyst for methane gas is formed on the surface of the porous platinum layer forming the anode electrode of the solid electrolyte element. ₂ is a solid electrolyte fuel cell characterized in that metal oxide particles composed of ₂ are dispersed and fixed. In the present invention, the solid electrolyte substrate is formed by a stabilized zirconia fired body to which yttria is added, and the cathode-side electrode is made of lanthanum strontium manganese oxide [(La _0.85 Sr _0.15 )
_0.90 MnO ₃ ].

According to the solid electrolyte fuel cell of the present invention, a metal oxide comprising CoNiO ₂ or CoO as a catalyst for oxidizing methane gas, which is blended in a porous platinum layer forming an anode electrode of the solid electrolyte element The oxidation reaction of methane can be promoted by particles or metal oxide particles composed of PdCoO ₂ as an oxidation catalyst for methane gas dispersed and fixed on the surface of the porous platinum layer. For this reason,
Ni-YSZ cermet solid electrolyte element 1 shown in FIG.
As compared with the solid electrolyte fuel cell having the fuel cell 10, the operating temperature range in which power can be stably generated can be widened. Further, as the methane gas supplied as the fuel, a dry methane gas which does not need to contain moisture in advance can be used. Among the solid electrolyte fuel cells according to the present invention, CoNi
A solid electrolyte fuel cell including a solid electrolytic element in which metal oxide particles made of O ₂ or CoO are blended in a porous platinum layer forming an anode electrode is a porous platinum layer forming an anode electrode. Power generation characteristics such as discharge current density and generated current density and thermal chemical stability compared with a solid electrolyte fuel cell having a solid electrolyte element in which metal oxide particles composed of PdCoO ₂ are dispersed and fixed on the surface of Is also excellent.

[0010]

FIG. 1 is a schematic diagram illustrating an example of a solid oxide fuel cell according to the present invention. The solid electrolyte fuel cell shown in FIG. 1 has 8 mol% of yttria (Y
_A YSZ fired body made of stabilized zirconia (YSZ) to which ₂ O ₃ ) is added is used as an oxygen ion conductive solid electrolyte substrate 10, and a solid electrolyte in which electrodes 12 and 14 a are formed on both surfaces of the solid electrolyte substrate 10. An element 16A is provided. Electrodes 12, 1 of this solid electrolyte element 16A
4a, the electrode 12 is made of lanthanum strontium manganese oxide [(La _0.85 Sr _0.15 ) _0.90 MnO ₃ ]
And used as a cathode. Oxygen is supplied to the electrode 12 side. On the other hand, the electrode 14a
Are used as cathodes and are substantially formed by a porous platinum layer. Methane gas as fuel is supplied to the electrode 14a side.

The oxygen (O ₂ ) supplied to the electrode 12 of the solid electrolyte element 16A shown in FIG. 1 is ionized into oxygen ions (O ²⁻ ) at the boundary between the electrode 12 and the solid electrolyte substrate 10, and this oxygen The ions (O ²⁻ ) are transferred to the solid electrolyte substrate 1
0 conducts to the electrode 14a. Oxygen ions (O ²⁻ ) conducted to the electrode 14a react with methane (CH ₄ ) gas supplied to the electrode 14a side, and water (H ₂ O), carbon dioxide (CO ₂ ), and hydrogen (H ₂ ) ), Carbon monoxide (CO)
Generate During this reaction, oxygen ions emit electrons, so that a potential difference occurs between the electrode 12 and the electrode 14a. For this reason, by electrically connecting the electrodes 12 and 14a by the extraction line 18, the electrons of the electrode 14a flow through the extraction line 18 in the direction of the electrode 12 (in the direction of the arrow) to extract electricity from the solid oxide fuel cell. Can be.

Electrode 1 of solid electrolyte element 16A shown in FIG.
4a is mainly formed by a porous platinum layer,
In this porous platinum layer, metal oxide particles 2 made of CoNiO ₂ or CoO as an oxidation catalyst for methane gas are used.
0, 20 ... are blended. The metal oxide particles 20, 20... Can promote an oxidation reaction between methane and oxygen ions (O ²⁻ ) conducted by the solid electrolyte substrate 10 to the electrode 14a, and the discharge current of the solid electrolyte fuel cell Power generation characteristics such as density and generated current density can be improved. Such an electrode 14a is formed by applying a mixed paste obtained by mixing a predetermined amount of metal oxide particles 20 made of pulverized CoNiO ₂ or CoO to a platinum paste on one surface side of a YSZ fired body, Medium, it can be formed by firing at 1300 ° C. for about 1 hour.

FIG. 2 is a schematic diagram of another example of the solid oxide fuel cell according to the present invention. The solid electrolyte fuel cell shown in FIG. 2 has the same structure as the solid electrolyte fuel cell shown in FIG.
A YSZ fired body made of stabilized zirconia (YSZ) to which 8 mol% of yttria (Y ₂ O ₃ ) is added is used as an oxygen ion conduction type solid electrolyte substrate 10, and electrodes 12 and 14 b are provided on both surfaces of the solid electrolyte substrate 10. Is formed on the solid electrolyte element 16B. Of the electrodes 12 and 14b of the solid electrolyte element 16B, the electrode 12 is made of lanthanum strontium manganese oxide [(La _0.85 Sr _0.15 ), similarly to the solid electrolyte fuel cell shown in FIG.
_0.90 MnO ₃ ] and used as a cathode. Oxygen is supplied to the electrode 12 side. On the other hand, the electrode 14b is used as an anode. Methane gas as fuel is supplied to the electrode 14b side.

The electrode 14 of the solid oxide fuel cell shown in FIG.
b shows a porous platinum layer 22a formed on one end surface of the solid electrolyte substrate 10, and metal oxide particles made of PdCoO ₂ serving as an oxidation catalyst for methane gas dispersed and fixed on the surface of the porous platinum layer 22a. And a layer 22b. The layer 22b can promote an oxidation reaction between methane and oxygen ions (O ²⁻ ) conducted by the solid electrolyte substrate 10 to the electrode 14b, and can improve the discharge current density and generated current density of the solid electrolyte fuel cell. Power generation characteristics can be improved. Such an electrode 14b is formed by applying a platinum paste to one surface side of a YSZ fired body at a predetermined thickness, and then firing in air at 1300 ° C. for about 1 hour to form a porous platinum layer 22.
a is formed. Next, on this porous platinum layer 22a,
Metal oxide particles 2 composed of PdCoO ₂ which has been pulverized in advance
After applying a mixed paste obtained by mixing a predetermined amount of 0 with an organic binder on one surface side of a YSZ fired body, the mixed paste was dried in air at 8
It can be formed by firing at 50 ° C. for about 3 hours.

The solid electrolyte element 16A shown in FIG. 1 or FIG.
The power generation characteristics and the like of the solid electrolyte element 16b shown in FIG. 3 were measured using the measuring device shown in FIG. The measuring device shown in FIG.
A first cylindrical body 34 made of ceramic is inserted into a space 32 maintained at a desired temperature in the furnace 30.
A second cylindrical body 36 made of ceramic is inserted from one of the open ends of the cylindrical body 36. The solid electrolyte element 16 is provided at the insertion end of the second cylinder 36 so that one end of the opening end of the second cylinder 36 is closed by the electrode 14 of the solid electrolyte element 16. In the vicinity of the electrode 14 of the solid electrolyte element 16, a methane gas supply pipe 38 for supplying dry methane gas substantially free of moisture at a predetermined flow rate is opened, and near the other open end of the second cylindrical body 36. Is provided with a discharge pipe 42 from which combustion gas such as methane gas is discharged. An oxygen supply pipe 40 for supplying oxygen at a predetermined flow rate is inserted from the other open end of the first cylindrical body 34 in the vicinity of the electrode 12 of the solid solid electrolyte element 16A or the solid solid electrolyte element 16B. A discharge pipe 44 from which the residue is discharged is provided at the other open end of the first cylindrical body 34. Further, a thermocouple 46 is inserted from the other opening end of the first cylindrical body 34 so that the ambient temperature in the vicinity of the solid electrolyte element 16 can be measured. The first
The two open ends of the cylindrical body 34 and the other open end of the second cylindrical body 36 are plugged with silicone rubber plugs 48a, 48b, 50, respectively.
Is blocked by

While measuring the ambient temperature in the vicinity of the solid electrolyte element mounted on the measuring device shown in FIG. 3 with a thermocouple 46, the furnace 30 is controlled to a desired temperature, and the discharge characteristic curve shown in FIG. Obtained. The discharge characteristic curve shown in FIG. 4 is obtained by measuring the extraction voltage and the extraction current extracted from both electrodes of the solid electrolyte element while changing the amount of the extraction current. In the graph of FIG. 4, the abscissa indicates the current density (the amount of extracted current per unit area of the electrode), and the ordinate indicates the extracted voltage. As is clear from the discharge characteristic curve shown in FIG. 4, as the amount of current taken out from the solid electrolyte element is increased (current density is increased), the taken-out voltage decreases, and the current density when the taken-out voltage becomes zero volts Is the maximum current density X. This maximum current density X represents the power generation capacity of the solid electrolyte element. As shown in FIG. 4, the maximum current density X was obtained by extrapolating the measured discharge characteristic curve until the extraction voltage became zero volt. The discharge characteristic curves shown in FIG. 4 were obtained for various solid electrolyte devices while maintaining the ambient temperature of the solid electrolyte device at 850 ° C. (1123 ° K), and the generated power density curves shown in FIG. 5 were obtained. The vertical axis in FIG. 5 is the power density (voltage × current density) and the horizontal axis is the current density. The curve of the generated power density shown in FIG. 5 is a convex curve, and the larger the point where the generated power density is maximum and the larger the area of the convex curve, the larger the amount of power generation.

Of the generated power density curves shown in FIG. 5, curves A and B are for the solid electrolyte element 16A shown in FIG. Curve A shows that the porous platinum layer forming the electrode 14a as an anode has Co as a catalyst for oxidizing methane gas.
The metal oxide particles 20, 20 made of NiO _2, a generation power density of the solid electrolyte device 16A was 5 wt% blended with respect to platinum, curve B, the metal oxide particles composed of conio ₂ 20, 20 · Solid electrolyte element 16A containing metal particles 20, 20,...
Shows the generated power density. Further, a curve F indicates the generated power density of the solid electrolyte element 16B shown in FIG. 2, that is, the electrode 14b as an anode is formed on the porous platinum layer 22a and the surface of the porous platinum layer 22a as an oxidation catalyst for methane gas. 5 shows a generated power density of a solid electrolyte element 16B formed by a layer 22b in which metal oxide particles made of PdCoO ₂ are dispersed and fixed. FIG. 5 also shows FIG.
The solid electrolyte element 106 used in the conventional solid electrolyte fuel cell shown in FIG.
4a, the generated power density (curve D) of the solid electrolyte element 106 formed of only porous platinum, Ni-
The generated power density (curve E) of the YSZ cermet solid electrolyte element 110, the electrode 104 as an anode shown in FIG.
The solid electrolyte element 200 (curve C) in which metal oxide particles 202 composed of PdCoO ₂ are blended in a porous platinum layer forming c is shown.

FIG. 6 shows the relationship between the solid electrolytic element and the operating temperature. Each of the curves shown in FIG. 6 is a curve showing the relationship between the maximum current density X and the temperature obtained from the discharge characteristic curves measured for various solid electrolytic devices, as shown in FIG.
The solid electrolyte elements corresponding to the curves A to E are:
This is similar to the case of FIG. As is clear from FIG. 6, the solid electrolyte element shows that the maximum current density increases as the ambient temperature (operating temperature) increases, in other words, the power generation capacity of the solid electrolyte element increases. The temperature on the horizontal axis in FIG. 6 is represented by an absolute temperature (K). As is clear from FIGS. 5 and 6, metal oxide particles 20 and 2 made of CoNiO ₂ were added to the porous platinum layer as a catalyst for oxidizing methane gas.
The solid electrolyte element 16A (curve A) provided with the electrode 16a formed by mixing 0... Has better power generation density and maximum current density than the Ni-YSZ cermet solid electrolyte element 110 (curve E). And its power generation capacity and power generation capacity are excellent. In addition, both of the solid electrolytic devices 16A and 16B used in the solid electrolyte fuel cells shown in FIGS. 1 and 2 have better generation than the solid electrolytic devices 106 and 200 used in the conventional solid electrolyte fuel electrons. It has a power density and a maximum current density, and has excellent power generation capacity and power generation capability.

However, the generated power density and the maximum current density of the Ni-YSZ cermet solid electrolyte element 110 shown in FIGS. 5 and 6 are the same as those of the solid electrolytic element 16A shown in FIGS.
16B, a solid electrolyte element 16 having an electrode 16a formed by mixing metal particles 20, 20,... Made of CoO as a catalyst for oxidizing methane gas in a porous platinum layer.
A (solid electrolyte element corresponding to curve B) and the surface of the porous platinum layer 22 a
Better than the generated power density and the maximum current density of the solid electrolyte element 16B (solid electrolyte element corresponding to the curve F) including the electrode 16b formed by the layer 22b in which metal oxide particles of dCoO ₂ are dispersed and fixed. looks like. However, the Ni-YSZ cermet solid electrolyte element 110 is the same as the electrodes 102, 1
After taking out the extraction voltage and the extraction current from the output current, changing the extraction current, measuring the extraction voltage, and ending a series of measurements, when the same measurement is performed again, even if the same extraction current amount, the low voltage is reduced. Will be presented. This is shown in the graph of FIG. 7 showing the relationship between the generated power density and the current density. In FIG. 6, “1st run” is the generated power density curve measured in the first measurement, “2nd run” is the generated power density curve measured in the second measurement, and “3rd run” is the third Each of the generated power density curves measured in the second measurement is shown. As is clear from FIG. 7, the performance of the Ni-YSZ cermet solid electrolyte element 110 gradually deteriorates in the direction of the arrow. In particular,
When the take-out current is increased, the deterioration increases.

On the other hand, in the solid electrolytic devices 16A and 16B used in the solid electrolyte fuel cells shown in FIGS. 1 and 2,
The Ni-YSZ cermet solid electrolyte element 110 does not show the deterioration of the generated power density shown in FIG. This is called C
The generated power density of the solid electrolyte element 16A including the electrode 16a made of a porous platinum layer containing the metal oxide particles 20, 20... made of oNiO ₂ was measured in the same manner as in the measurement of the generated power density shown in FIG. FIG. 8 shows the results of repeated measurements. As is clear from FIG. 8, no deterioration in the performance of the solid electrolyte element 16A was observed during the three measurements. Further, the ambient temperature at which the extraction voltage of the Ni-YSZ cermet solid electrolyte element 110 is stabilized is 92, as shown in FIG.
5 ° C. (1198 ° K) or more, preferably 950 ° C. (12
23 ° K) or more, and the ambient temperature is 925 ° C. (119 ° C.).
Below 8 ° K), the extraction voltage becomes unstable. In FIG. 9, the supply of methane gas was stopped during the period in which the ambient temperature was changed, and the supply of methane gas was started when the ambient temperature became the desired temperature and stabilized.

On the other hand, the Ni-YSZ cermet solid electrolyte element 110 operates stably at 925 ° C. (1198 ° C.).
Under the ambient temperature of K) or more, the performance of the solid electrolyte element 110 is greatly deteriorated. This is the solid electrolyte substrate 114
This is thought to be due to the sintering of the Ni particles contained in the Ni or the lowering of the electrode reaction activity due to the adhesion of carbon to the electrode surface. In this regard, in the solid electrolytic devices 16A and 16B used in the solid electrolyte fuel cells shown in FIGS.
A stable extraction voltage can be obtained even at an ambient temperature in a region where the extraction voltage of the YSZ cermet solid electrolyte element 110 is unstable, and the solid electrolyte element 16A can be obtained even at an ambient temperature of 925 ° C. (1198 ° K) or higher. The performance of 16B is stable.

As described above, the solid electrolyte fuel cell shown in FIGS. 1 and 2 is a Ni-YSZ cermet solid electrolyte element 1
As compared with the solid electrolyte fuel cell using the fuel cell 10, stable power generation can be performed. Only, a porous platinum layer 22a,
The solid electrolyte element 16B shown in FIG. 2 having an electrode 16b formed by a layer 22b in which metal oxide particles made of PdCoO ₂ are dispersed and fixed on the surface of the porous platinum layer 22a has an atmosphere temperature of 900 ° C. (1173 °
If K) is exceeded, thermal decomposition of the layer 22b made of PdCoO ₂ tends to occur easily. In this respect, metal oxide particles 2 made of CoNiO ₂ or CoO are formed on the porous platinum layer.
The solid electrolyte element 16A shown in FIG. 1 including the electrode 14a formed by mixing 0, 20,.
Even when the temperature exceeds 0 ° C. (1173 ° K), no thermal decomposition or the like occurs,
It has good heat resistance. Also in the solid electrolyte element 16A shown in FIG. 1, the solid electrolyte element 16A including the electrode 14a formed by blending CoNiO ₂ as the metal oxide particles 20, 20,... Is evident from FIGS. Thus, it exhibits the best generated power density and the maximum current density, and shows the best power generation capacity and power generation capacity. In order to obtain the solid electrolyte element 16A including the electrode 14a in which the metal oxide particles 20, 20... Made of CoNiO ₂ are mixed in a porous platinum layer, first, a reagent CoO and a reagent Ni are used.
O, and each powder was mixed in air at 1300 ° C. for 24 hours.
After firing for about an hour, pulverization gives C
The metal oxide particles 20 made of oNiO ₂ are obtained. Next, a mixed paste obtained by mixing a predetermined amount of the metal oxide particles 20 with a platinum paste is applied to one surface side of a YSZ fired body, and then fired at 1300 ° C. in the air for about 1 hour. Thus, the solid electrolyte element 16A can be obtained.

The electrode 14a in which metal particles 20, 20,... Made of CoNiO ₂ are mixed in a porous platinum layer
The ambient temperature at which the solid electrolyte element 16A having the highest performance can exhibit the highest performance is 700 to 950 ° C. In such a temperature range, the Ni-YSZ cermet solid electrolyte element 1
Reference numeral 10 denotes a region where the extraction voltage becomes unstable. As described above, the solid electrolyte element 1 capable of exhibiting high performance at a relatively low temperature
By using 6A, the condition of heat resistance of components forming the solid oxide fuel cell is relaxed. Therefore, the manufacturing cost of the solid oxide fuel cell can be reduced.

[0024]

According to the solid electrolyte fuel cell of the present invention, the temperature range in which the performance can be sufficiently exhibited is wide and good power generation characteristics are exhibited. For this reason, the power generation by the solid electrolyte fuel cell can be performed more efficiently, and the production cost of the solid electrolyte fuel cell can be reduced. As a result, the solid electrolyte fuel cell can be further spread. it can.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of a solid oxide fuel cell according to the present invention.

FIG. 2 is a schematic diagram for explaining another example of the solid oxide fuel cell according to the present invention.

FIG. 3 is a schematic diagram of a measuring device for measuring power generation characteristics and the like of a solid electrolyte element.

FIG. 4 is a graph for explaining discharge characteristics of the solid electrolyte element measured by the measuring device shown in FIG.

FIG. 5 is a graph showing a relationship between a generated power density and a taken-out current density of various solid electrolyte devices.

FIG. 6 is a graph showing the relationship between the maximum current density and the temperature of various solid electrolyte devices.

FIG. 7 is a graph showing a change in generated power density when the generated power density of a conventional solid electrolyte element is repeatedly measured.

FIG. 8 is a graph showing a change in generated power density when the generated power density of the solid electrolyte device according to the present invention is repeatedly measured.

FIG. 9 is a chart illustrating a relationship between an ambient temperature and a take-out voltage of a conventional solid electrolyte element.

FIG. 10 is a schematic diagram for explaining an outline of a conventional solid oxide fuel cell.

FIG. 11 is a cross-sectional view illustrating a structure of a solid electrolyte element used in a conventional solid oxide fuel cell.

FIG. 12 is a cross-sectional view for explaining an improved example of a solid electrolyte element used in a conventional solid oxide fuel cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Solid electrolyte substrate 12 Electrode (cathode) 14a, 14b Electrode (anode) 16A, 16B Solid electrolyte element 18 Lead wire 20 Metal particle

[Procedure amendment]

[Submission date] October 20, 1999 (1999.10.
20)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0002

[Correction method] Change

[Correction contents]

[0002]

2. Description of the Related Art Solid electrolyte fuel cells can be expected to have higher power generation efficiency than power generation efficiency such as thermal power generation. As shown in FIG. 10, such a solid electrolyte fuel cell has a yttria (Y ₂
O ₃ ) -added stabilized zirconia (hereinafter simply referred to as YS)
Z (hereinafter sometimes referred to as Z) (hereinafter referred to as YSZ).
(Which may be referred to as a fired body) as an oxygen ion conduction type solid electrolyte substrate 100.
A solid electrolyte element 106 having electrodes 102 and 104a formed on both surfaces of the solid electrolyte element is provided. This solid electrolyte element 1
06 among the electrodes 102 and 104a, lanthanum strontium manganese oxide [(La _0.85
Sr _0.15 ) _0.90 MnO ₃ ] and used as a cathode . Oxygen or an oxygen-containing gas is supplied to the electrode 102 side. The other electrode 104a is
It is formed by a porous platinum layer and used as an anode . Methane gas as fuel is supplied to the electrode 104a side.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0003

[Correction method] Change

[Correction contents]

[0003] The solid electrolyte element 106 shown in FIG.
(O 2) supplied to the electrode 102 of _Two) Is the electrode 102
Oxygen ions (O 2) at the boundary between^2-)
The oxygen ion (O^2-) Is a solid electrolytic
Conducted to the electrode 104 by the quality substrate 100. Electrode 1
Oxygen ion (O^2-) Is the electrode 104
aSupplied to the reactor (CH_Four) Reacts with gas and water (H
_TwoO), carbon dioxide (CO_Two), Hydrogen (H_Two),monoxide
Carbon (CO) is produced. During this reaction, oxygen
Since ON emits electrons, the electrodes 102 and 104a
And a potential difference is generated between them. Therefore, the electrodes 102, 10
4a by electrically connecting the
And the electrons on the electrode 104a move in the direction of the electrode 102 (the direction
Flow from the solid electrolyte fuel cell
I can take my mind. In addition, the fixation shown in FIG.
The operating temperature of the body electrolyte fuel cell is about 1000 ° C.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction contents]

Although the solid electrolyte element 106 shown in FIG. 10 has durability against a high operating temperature, it has low power generation characteristics such as a generated current density and a discharge current density, and improvement of these properties has been demanded. . For this reason, the solid electrolyte element 110 shown in FIG. 11 is being used. The solid electrolyte element 110 is substantially formed by a solid electrolyte substrate 112 made of YSZ.
The electrode 104b is formed on one end of the electrode 12 as an anode . The electrode 104b includes YSZ forming the solid electrolyte substrate 112, cermet particles 114 made of nickel (Ni) and nickel oxide (NiO),
.. Are formed as a mixture.
A cathode formed on the other end of the solid electrolyte substrate 112
Electrode 102 as over-de, like the electrode 102 of the solid electrolyte device 106 shown in FIG. 10, lanthanum strontium Chiu
Consists of mumanganese oxide .

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction contents]

[0010]

FIG. 1 is a schematic diagram illustrating an example of a solid oxide fuel cell according to the present invention. The solid electrolyte fuel cell shown in FIG. 1 has 8 mol% of yttria (Y
_A YSZ fired body made of stabilized zirconia (YSZ) to which ₂ O ₃ ) is added is used as an oxygen ion conductive solid electrolyte substrate 10, and a solid electrolyte in which electrodes 12 and 14 a are formed on both surfaces of the solid electrolyte substrate 10. An element 16A is provided. Electrodes 12, 1 of this solid electrolyte element 16A
4a, the electrode 12 is made of lanthanum strontium manganese oxide [(La _0.85 Sr _0.15 ) _0.90 MnO ₃ ]
And used as a cathode. Oxygen is supplied to the electrode 12 side. On the other hand, the electrode 14a
Are used as anodes and are substantially formed by a porous platinum layer. Methane gas as fuel is supplied to the electrode 14a side.

Continuing from the front page (72) Inventor Yasunobu Inoue 1603-1 Kamitomiokacho, Nagaoka City, Niigata Prefecture Inside Nagaoka University of Science and Technology (72) Inventor Shigeaki Suganuma 711 Kurita Cross Section, Toda, Shinko Electric Industry Co., Ltd. F term (reference) 5H018 AA06 AS01 DD01 EE03 EE12 EE13 5H026 AA06 EE02 EE12 EE13

Claims (3)

[Claims] 1. A solid electrolyte device comprising electrodes formed on both surfaces of an oxygen ion conduction type solid electrolyte substrate, wherein oxygen or an oxygen-containing gas is supplied to a cathode electrode of the solid electrolyte device. In a solid electrolyte fuel cell in which methane gas as fuel is supplied to an anode electrode, a porous platinum layer substantially forming an anode electrode of the solid electrolyte element contains C as an oxidation catalyst for methane gas.
A solid oxide fuel cell comprising metal oxide particles comprising oNiO ₂ or CoO. 2. A solid electrolyte device comprising electrodes formed on both surfaces of an oxygen ion conduction type solid electrolyte substrate, wherein oxygen or an oxygen-containing gas is supplied to a cathode electrode of the solid electrolyte device, In a solid electrolyte fuel cell in which methane gas as fuel is supplied to an anode electrode, PdC as an oxidation catalyst for methane gas is formed on a surface of a porous platinum layer forming an anode electrode of the solid electrolyte element.
A solid oxide fuel cell, wherein metal oxide particles made of oO ₂ are dispersed and fixed. 3. The solid electrolyte substrate is formed by a stabilized zirconia fired body to which yttria is added, and the cathode-side electrode is formed by lanthanum strontium manganese oxide [(La _0.85 Sr _0.15 ) _0.90 MnO ₃ ]. The solid electrolyte fuel cell according to claim 1 or 2, wherein